The motorcycles currently known in the prior art typically comprise a transmission mechanism which deliver a motion from the crankshaft to the drive wheel in two phases. A primary transmission extends from the crankshaft to the gearbox or gear group, whereas a secondary transmission is provided to extend the motion from the gearbox or gear group to the drive wheel.
The primary transmission is typically provided in the form of chain or gears. On the other hand, the secondary transmission can be provided as a conventional link chain or any other suitable transmission, such as for example, shaft, belt, etc.
One example of the prior art motorcycle is disclosed by the inventor's own Spanish patent P9200916. In this motorcycle, the primary transmission is placed between the engine crankshaft and the gearbox. The transmission elements of the secondary transmission and the tertiary transmission are placed at the same side of the motorcycle, with respect to its longitudinal axis.
This design is resulted in a substantial width of the motorcycle, which causes an ergonomic problem and requires an additional space for driving and parking.
From the ergonomic point of view, it is essential to place the components of the motorcycle in a position, so as not to disturb the motorcycle rider, especially when he/she rides standing up or in an upright position.